It is a flat one piece button, often referred to as a coin button, due to the shape. You can see traces of the loop(or shank), for attachment to clothing) in the area near the crown. The word ‘double’ refers to the quality of plating. The second word is probably ‘gilt’. Some backmarks will say ‘treble gilt’, ‘rich orange’, ‘extra quality’, etc. You can often date buttons to a specific maker and year according to the wording, symbols and other such things such as the rows of dots encircling the shank. This one you have is probably from the time period 1800-1820. Occasionally there would be a design on the face of the button, but most of them were plain. Maybe you could try to take a few more pictures of each side to see if we can get clearer images, as i may be able to determine a more exact date, and also the maker of your button